1. Field of the Invention
The present invention relates to a wafer or chip structure, a stacked structure and methods for fabricating the same, and more particularly to a self-aligned wafer or chip structure, self-aligned stacked structure and methods for fabricating the same.
2. Description of Related Art
With the development of science and technology, more and more functions must be integrated in a single application carrier. The most common application carriers are mobile phones closely related to every individual and memory card elements for storing mass digital information. In addition, with the human's endless requirements for information bandwidth, more and more semiconductor devices are designed towards the trend of having a high frequency or ultra-high frequency, and thus the current wire bonding technique cannot satisfy the requirements of the above applications any more.
Recently, more and more constructions are designed as through silicon vias (TSV) with a high-density three-dimensional stacked structure and an ultra-short electrical wiring distance. For example, some US patents, such as U.S. Pat. Nos. 7,091,124 and 6,936,913, have proposed several structures and methods for stacking a plurality of chips together, which can greatly reduce the volume of the construction, increase the capacity of the construction, and significantly reduce the high parasitic inductance effect of the high frequency electrical signal between chips due to a long electrical connection length. However, how to precisely align and stack the chips together to ensure the well electrical connection between chips is one of the most important tasks. Moreover, in all those proposed stacking methods, one stacking process must be performed together with one reflow process, so as to complete the whole stacked construction. Therefore, the existed methods have the disadvantage of being quite time consuming.